Who is it that serves and protects?!?

We got home this afternoon to find a pitbull sitting out in our yard! No collar and it was dirty and mangy. I called 911 to notify them that a wild dog was sitting out side my house and the kids were to terrified to get out of the car. While the dispatcher was on the phone I rolled down the window to yell at it and to tell it to get away. Well what happened next i will never forget! It full on charged our car and before Katelin could get the window up it jumped and clawed the side of the car until it could get in!!! What was a mother suppose to do when a 150 pound pit bull is loose in your car with your children. Cody and Weston jumped out but Katelin had jumped into the back and Savannah was still strapped in her car seat!!! I don't know how I did it it was all a blur but I somehow Katelin and Savannah in my arms so fast!!! We hurried and shut the doors and locked it inside. Luckily the dispatcher was still on the other line. She had heard everything. She said she was sending someone out right away. Well 10 minutes later no one showed up but instead I got a nice call from the Grant County Sheriff letting me know that there was nothing they could do we were out of Animal Control's jurisdiction. He continued to tell me that all I could do was open the door and let him go!!!!! I said what if he bites me or one of my kids could I shoot him? He said no. So I am very frustrated!! As we speak a pit bull sits in my car and there is nothing I can do about it!